1. Field of the Invention
The present invention relates to a network connecting system, a mobile terminal, and a network accessing method. More particularly, the present invention relates to a local network connecting system, a mobile terminal, and a local network connecting method, in which a mobile terminal is VPN-connected to the local network through another local network.
2. Description of the Related Art
Conventionally, as a content access service of a packet switching type, there are an Internet access, a content access based on a local address, a VPN access for a connection to a remote site through tunneling and the like. The local content access is the type, for example, such as a so-called intranet in which an user in a company accesses a local server by a local address. Conventionally, there are many examples of company network connections. On the other hand, as the VPN access, there is an example of accessing a company server from outside the company. Also in this case, similarly to the local content access, using the local address to carry out a communication.
Japanese Laid Open Patent Application (JP-P2004-104699A) discloses a network system in which an electronic content table terminal installed in LAN (Local Area Network) transmits a data based on a local address assigned to an electronic content table server within a first network address.
Japanese Laid Open Patent Application (JP-P2004-104699A) discloses the system in which a KARAOKE delivery network is used as an example, and the electronic content table terminal is connected to a delivery sever installed at a center by VPN connection using the local address, and simultaneously even is connected to a branch of electronic content table server using another local address. This disclosed example is the system limited network for the KARAOKE delivery system. That is, since the destination local addresses for the VPN and for the direct connection are set for a router, the addresses for both of them are always different values.
Japanese Laid Open Patent Application (JP-P2002-335273A) discloses a remote maintenance method, in which a maintaining center in a VPN assigns a global address with a terminal, that is in a local network and can VPN-connect to another local network, as a VPN NAT (Network Address Translation) local IP address. Since NAT is established in a local network of the destination, the terminal can be VPN-connected to local network via the NAT using the VPN NAT local IP address.
Japanese Laid Open Patent Application (JP-P2004-229299A) discloses a network connecting apparatus for preparing and assigning a local address that is not used to the network, if duplicate network addresses are assigned in a plurality of local networks connected to each other.
In Japanese Laid Open Patent Application (JP-P2004-229299A), home gateways are installed in a plurality of local networks, and they assign new local addresses. For this reason, as the number of the local networks which are connected to the home gateways is increased, the number of the local address pools to be newly prepared in order to avoid the duplication is decreased, and there is a possibility that the connection becomes finally impossible.
In Japanese Laid Open Patent Application (JP-P2001-148718A), dissemination server is installed in a computer network, the dissemination server manages a address list describing in-use address in the network. When a terminal obtains a network address, the terminal obtains unused address in the network from the dissemination server.
In Japanese Laid Open Patent Application (JP-P2001-345843A), IP connection controller has a table describing a relation of a ID of a local network and network address for virtual excusive path. The controller routs a packet to virtual excusive path accordance with their ID based on the table. And IP network terminal send the packet received from the controller to a local network corresponding to the path.
In Japanese Laid Open Patent Application (JP-P2002-77275A), A system transmits a packet received from an identifiable closed network to another network. It provide for a routing table describing relation of ID of the closed network and IP address assigned with the closed network. It determines a destination of a packet based on the table.
In Japanese Laid Open Patent Application (JP-P2003-188901A), A NAT router has a NAT table describing a relation of a global address and a local address of a host computer in a second network. A DNS for VPN has an information of a name and the local address of the host computer. When a terminal in a first network send packet to the host computer, it sends a name of the host computer to the DNS and obtains the global address based on the name from the NAT router.
Conventionally, when the local content access and the VPN access are carried out through the same local network, since both of destination servers have no relation to each other, they may accidentally have the same local address. For this reason, when the user uses any one of the services and desires to start a communication with a partner of this address, the destination of the packet passed to an IP stack of a kernel from an application is judged only in accordance with a destination address value. It cannot be judged to send To which interface of the VPN connection and the local server connection.
On the other hand, conventionally, as the content accessed based on a local address (hereafter, referred to as local content), there are many examples of the connections to the network at the companies. However, there is a possibility where the utilization of a different local content is popular in future. That is, in the conventional case, the local content installed in a local network for established the Internet connection for example, PPP (Point to Point Protocol)—connection network, a packet network of a 3G (3 Generation) cellular, and a hot spot in a radio LAN, the local contents are installed in various networks that exist on the way to the entrances of the Internet. For example, a 3G cellular network provides a service of connection to the Internet through RAN (Radio Access Network) and CN (Core Network). However, a request to establish the content specialized for each area and attain a profit is generated even in the entrepreneur of a RAN or a CN established for a carrier or a hot spot. In this case, the scene where the local content is used while the VPN accessing is increased. Thus, It is increased problems to use the same local address of the VPN access and using of the local content.